High vacuum pump with air jet having automatic cut-in valve

ABSTRACT

A HIGH VACUUM PUMP PROVIDED WITH AN AIR JET THAT IS AUTOMATICALLY CUT INTO THE SYSTEM UPON THE ATTAINMENT OF A PREDETERMINED VACUUM LEVEL. THE VALVE ARRANGEMENT INCLUDES PNEUMATICALLY OPERATED VALVES WHICH BRING THE AIR JET ASSEMBLY INTO OPERATION, USING THE VACUUM PUMP AS A SECOND STAGE. THE PNEUMATIC VALVES ARE MADE OPERATIVE BY A VACUUM SWITCH CONTROLLING A SOLENOID AND A DOUBLE-ACTING CONTROL VALVE.

Jan. 19, 197 1 I I. 6. JENNINGS 3,556,681

HIGH VACUUM PUMP WITH AIR JET HAVING AUTOMATIC CUT-IN VALVE Filed Feb. '5, 1969 '2 Sheets-Sheet 1 Tlc i. 66

COMPRESSED fxxmusrlds'A/r Jan. 19, 1971 l. c. JENNINGS HIGH VACUUM PUMP WITH AIR JET HAVING AUTOMATIC CUT-IN VALVE Filed Feb. :5, 1969 2 Sheets-Sheet 2 lvl M IV. T l w l Q I! M z r a z N 7. 6 w h 4 4 M w 4; N w m. 1: rllllll. Mm 1 M .l e m Z l 3 4 L w.

M 6 w W 1 United States Patent O 3,556,681 HIGH VACUUM PUMP WITH AIR JET HAVING AUTOMATIC CUT-IN VALVE Irving C. Jennings, Nash Engineering Co.,

South Norwalk, Conn. Filed Feb. 3. 1969, Ser. No. 795,981 Int. Cl. F04b 23/04, 23/08, 41 /06 U.S. Cl. 417-87 8 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Prior U.S. Pats. Nos. 3,064,878 and 3,239,131 are directed to constructions in which high vacuum pumps are utilized and which incorporate cut-in valves after the hogging or pull-up operation of an evacuation system. Upon the attainment of a certain vacuum level in the system an air jet or a supersonic jet diffuser becomes operational.

Similarly in the present construction, the ejector pump is retained in a non-operative condition in the system until the vacuum therein has reached a predetermined degree. When the vacuum has reached this particular degree, the ejector pump becomes operative and thereby enables the over-all system to attain a higher degree of vacuum than that reached by the primary vacuum pump alone. It should be noted that at this point the primary vacuum pump becomes the secondary pump while the jet pump becomes the primary pump. Thus, when the ejector pump is brought into the system after the primary pump has evacuated the system to the aforesaid predetermined degree of vacuum, a supersonic fluid flow is produced in the system. This supersonic flow is a combination of a primary and secondary stream of fluid. In this case, the primary fiuid is withdrawn from the container to be evacuated by the primary pump and a secondary stream is withdrawn from a source, such as the atmosphere, through the utilization of the vacuum produced by the primary pump. It is, therefore, apparent that a high efficiency evacuation system is provided by the present arrangement which includes automatic means for controlling the operation of the secondary ejector pump after a predetermined degree of vacuum has been attained by a primary pump. In the present case the automatic cut-in of the air jet is accomplished by means of a vacuum switch which operates a solenoid. The solenoid further controls a valve in the form of a double-acting piston which opens and closes the various lines to the pneumatic cylinders. The pistons in these pneumatic cylinders are connected to valves in the main line and an additional conduit circuit respectively. Thus, by the proper movement of the pistons 3,556,681 Patented Jan. 19, 1971 ice directed to a well known air ejector process in which an evacuator in the form of a conventional vacuum pump and at least one supersonic jet diffuser are arranged in a system for increasing the useful range of higher vacuum. Thus, the present system obtains higher vacuums than any comparable system and in addition, reduces strain on the apparatus, thereby avoiding irregular operation of the system and hence extending the normal life of the evacuator or the vacuum pump without expenditure of additional power.

BRIEF DESCRIPTION OF THE DRAWINGS This invention is illustrated by way of example in the accompanying drawing which form part of this application and in which:

FIG. 1 is a partial elevation view and a partial sectional view of the high vacuum pumping system constructed in accordance with the teachings of the present invention, and in one condition thereof; and

FIG. 2 is a partial elevational and a partial sectional view of another condition of the present high vacuum pumping system constructed in accordance with the teachings of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Reference is now made particularly to the drawings, in which FIG. 1 discloses the apparatus that utilizes a standard primary vacuum pump 10 driven by a motor (not shown). The pump 10 may be a conventional liquid ring pump and an intake manifold 12 is connected to the dual inlets 14 thereof. The intake manifold 12 is in fluid connection with the conduit 16 and the latter may be connected to a condenser (not shown), or other apparatus to be evacuated.

An additional conduit circuit is referred to generally by the numeral 18 and becomes operative by means of the movement of valves 20 and 22 within their respective valve housings 24 and 26. Valve housing 26 is provided with a valve seat 28 while housing 24 is provided with an upper valve seat 30 and a lower valve seat 32.

The movement of valves 20 and 22 in their respective housings 24 and 26 are caused by the movement of pneumatic pistons 34 and 36 in their respective cylinders 38 and 40. Piston 34 is connected to valve 20 by means of a piston rod 42, while piston 36 is connected to valve 22 by means of piston rod 44. The pistons 34 and 36 are operated by a compressed air supply in line 46 and the exhaust air is conducted through line 48. It is within the scope of the present invention to use hydraulicallyoperated pistons to move valves 20 and 22 in place of the air-operated pistons. I

A solenoid referred to generally by the numeral 50 is energized or de-energized by means of a diaphragmoperated vacuum switch 52, the latter being connected through pipe 51 to a source of vacuum, for example, a condenser (not shown) in the system.

The solenoid 50 is operatively connected to a doubleacting control piston 62, the latter being slidably operated in cylinder housing 64. Conduits 66 and 68 are connected from opposite ends of cylinder housing 64 to the solenoid 50. Conduit 66 is directly connected to the top of plunger 70 in solenoid 50 and the cylinder housing 64 is provided with an opening 72 directly under the path of travel of plunger 70. The cylinder housing 64 additionally is provided with a compressed air connection 74 and an exhaust vent 76.

Thus, when the system is started up and operating in the pulling-up or hogging stage, the solenoid 50 is energized and the air pressure and exhaust of the system follow the paths indicated by the arrows for both lines 46 and 48 in FIG. 1. In this case, the air pressure from the cylinder housing 64 is conducted through line 46 since the double-acting piston 62 has moved to the right thereby unblocking the line 46 and the compressed air then enters the top of the cylinder 38 and the bottom of cylinder 40. Accordingly, valve 20 is moved downwardly to a position on valve seat 28 while valve 22 is moved upwardly to a position on valve seat 30. The line 48 becomes the exhaust line and the compressed air is evacuated from the apparatus through the cylinder housing 64 and finally to the atmosphere through exhaust vent 76. In this condition of the system, the additional conduit circuit 18 is blocked off and the primary fluid stream indicated by the arrows A flows from the system being evacuated through conduit 16 directly into the connection 17 and then into the intake manifold 12 of the pump 10. The stream flows through pump and is then vented to the surrounding atmosphere through an exhaust tube (not shown).

Referring now to FIG. 2, and the condition when a certain level of vacuum is attained during the aforesaid pulling-up or hogging operation, which is approximately 26 inches, the vacuum switch 52 becomes operative causing the plunger 70 of the solenoid 50 to drop to a location where it blocks the opening 72 of the cylinder housing 64. When this occurs, compressed air is directed from conduit 66 through the plunger chamber to conduit 68 and into the right hand end of cylinder housing 64 thereby forcing the double-acting piston 62 to the left. Since line 48 is now unblocked compressed air is supplied through. line 48 and the exhaust is evacuated through line 46. Compressed air enters the top of cylinder 40 and the bottom of cylinder 38 and the piston 36 moves downwardly taking with it the valve 22 which moves from valve seat 30 to valve seat 32. Simultaneously, the piston 34 is caused to move upwardly taking with it the valve to abut the upper internal part of valve housing 26.

With the valves 20 and 22 in the positions shown in FIG. 2 the additional conduit circuit is opened and the primary fluid stream is caused to flow around the additional circuit 18 in the manner indicated by the arrows A. When this occurs, a secondary or ejector pump 58 becomes operative and the ejector pump causes a fluid flow indicated by the arrows B which joins the primary fluid stream A. Thus, when the predetermined degree of vacuum has been achieved a supersonic fluid flow is produced in the pump. The two streams are mixed in the conduit circuit 18 where the mixed circuit is decelerated thereby increasing the pressure of the system and reducing the amount of work required to operate pump 10. It should be noted that the pneumatically-operated valves 20 and 22 are operated automatically by means of the vacuum switch 52 and solenoid 50, and the air jet assembly is entirely shut off from the system until a certain vacuum is reached therein.

What is claimed is:

1. A high vacuum evacuation system comprising a primary vacuum pump, a suction conduit connecting a device to be evacuated with said primary pump during the hogging operation of said primary pump, an additional conduit circuit, a plurality of co-acting valves for connecting and disconnecting said additional conduit circuit to said suction conduit, an ejector pump in communication with said additional conduit circuit for operating in series with said primary vacuum pump for enablng the system to attain a higher degree of vacuum than that reached by the primary pump alone, a vacuum-operated switch responsive 19 @119 a uum n said device to be evacuated, a fluid-operated device constituting a pair of pistons each in respective cylinders, supply and exhaust lines for directing fluid to and from each cylinder, said fluid-operated device being operatively connected to said valves, means for supplying fluid to said fluid-operated device to move said valves, the latter being controlled by said switch whereby when said valves are in a predetermined position said additional conduit is connected to said suction conduit and said ejector pump becomes fully operative.

2. A high vacuum evacuation system as claimed in claim 1 wherein said pistons are pneumatically operated.

3. A high. vacuum evacuation system as claimed in claim 1 further comprising a solenoid, a control valve arrangement for opening and closing said supply and exhaust lines controlled and said solenoid, and said vacuumoperated switch being connected to said solenoid for operating the latter whereby said valve arrangement is selectively operated to open and close said supply and exhaust lines to said fluid-operated device.

4. A high vacuum evacuation system as claimed in claim 1 wherein said pistons are moved in opposite directions in order to operate respective valves. thereby selectively connecting said additional conduit circuit to said suction conduit.

5. A high vacuum evacuation system as claimed in claim 1 wherein said pistons are moved in the different directions in order to operate respective valves thereby selectively disconnecting said additional conduit circuit from said suction circuit.

6. A high vacuum evacuation system as claimed in claim 3 wherein the control valve arrangement is a cylinder having ports therein, and a double-acting piston in said cylinder, said piston being movable in said cylinder to open and close respective ports, and conduits connecting said valves to said ports whereby said fluid is selectively conducted and exhausted from said valves.

7. A high vacuum evacuation system as claimed in claim '6 wherein the cylinder is provided with an opening, said solenoid having a plunger positioned directly over said opening, said plunger being normally spaced from said opening but moved to block said opening upon the attainment of a predetermined amount of vacuum in the system.

8. A high vacuum evacuation system as claimed in claim 1 wherein said valves block ofl said additional conduit circuit from said system in one position thereof, and in another position thereof unblock said additional conduit circuit from said system in order to permit the connection of said additional conduit circuit to said suction conduit.

References Cited UNITED STATES PATENTS 312,644 2/1885 K-ux 230-45X 1,415,406 5/1922 Scanes 230111 2,085,942 7/1937 Bancel et al 230-111UX 2,124,620 7/1938 Kirgan 230--111 2,492,075 12/1949 Van Atta 230-45X 2,971,691 2/1961 Lorenz 23(l45 3,239,131 3/1966 Whyte 230111X MARK NEWMAN, Primary Examiner W. J. KRAUSS, Assitant Examiner US. Cl. X.R. 417-20. 

